Certain substrates are desirably coated in a vacuum simultaneously on both planar faces of the substrate. In particular, Winchester or other hard magnetic discs are formed by simultaneously vacuum sputtering magnetic material onto opposite planar faces of a non-magnetic substrate. It is known that it is desirable to hold such a disc vertically during the coating operation to minimize the problem of particulates settling on the disc surface; the particulates have a tendence to be generated in a vacuum sputtering system.
One prior art structure for holding substrates on edge is disclosed in commonly assigned Coad, et al, U.S. Pat. No. 4,311,427, issued Jan. 19, 1982. In the patent, a substrate disc is held on edge by engaging a vertically extending groove in a lifting blade. The blade is raised so that the groove of the blade engages an edge of the substrate, while the substrate is in a holder. The blade then raises the substrate, while holding the substrate on edge. In a prior proposal for using the lifting blade structure of the patent, a magnetic disc substrate is lifted by the blade to a position where the substrate parallel faces are simultaneously coated with magnetic material. During the coating operation, the substrate rests in the groove in the blade, so that a small portion of the substrate is shadowed or obscured from the coating material. Thereby, this small portion of the substrate remains uncoated, which has been perceived as a problem in manufacturing hard magnetic discs because every square millimeter of the disc is desirably employed to enable the maximum amount of data to be loaded into the disc. After the substrate has been coated, it is lowered from the coating position by retracting the blade downwardly. The substrate returns to the holder, thence it is transported to another area, such as another coating station in the vacuum, or to an unloading vacuum lock station.
It is, accordingly, an object of the present invention to provide a new and improved apparatus for and method of coating substrates in a vacuum wherein the substrates are so supported that during the coating operation no portion of the holding structure provides any obstruction between the face of the substrate being coated and the source of the coating material which is deposited on said face.
Another object of the present invention is to provide a new and improved apparatus for and method of simultaneously coating opposite faces of a non-magnetic disc shaped substrate held on edge during the coating operation so that the parallel faces of the substrate are vertically oriented, wherein the substrate is coated completely to the edges thereof with magnetic material.
Another object of the present invention is to provide a new and improved apparatus for and method of supporting a thin, generally circular substrate having opposite faces, and wherein the holding means does not contact or cover any portion of said faces.
Another object of the present invention is to provide a substrate particularly adapted to be supported such that coating material can be deposited onto one or both faces of the substrate to the edges thereof.
It is another object of the present invention to provide a coated substrate formed by mounting parallel, planar faces of the substrate in a vertical plane while the faces are simultaneously coated and wherein material is deposited onto the faces to the edges thereof.